1. Field of the Invention
The present invention relates to a scheme of adjusting ambient brightness received by shutter glasses, and more particularly to shutter glasses, and a corresponding electronic apparatus and method for dynamically adjusting the ambient brightness received by the shutter glasses when the shutter glasses operates under a two-dimensional image viewing mode.
2. Description of the Prior Art
Due to recent developments in video technology, users are pursuing three-dimensional (3D) and more real video displays as opposed to high quality images. Currently, there are two techniques for presenting a 3D video display. The first technique uses a video display apparatus which collaborates with 3D glasses (e.g. anaglyph glasses, polarization glasses or shutter glasses) while the second technique directly uses a video display apparatus without any accompanying 3D glasses.
The above-mentioned shutter glasses include two shutter lenses, which allow a user's left eye to see left-eye images and the user's right eye to see right-eye images via properly switching the shutter lens between an open state and a closed state.
When the user wears the shutter glasses, the brightness of a display area perceived by the user (e.g. the brightness of the 3D image displayed by the display screen) may be different from the ambient brightness beyond the display area as perceived by the user (i.e. the brightness of the ambient environment not belonging to the display screen). For example, the light beams of the ambient environment may not particularly undergo polarization processing, and the polarizer included in the shutter lens structure of the conventional shutter glasses will therefore cause the ambient brightness to have a significant decrease. When the liquid crystal layer in the shutter lens structure of the shutter glasses is in an open state, at least 50% of the ambient light is filtered by the polarizer, resulting in the ambient brightness perceived by the user being only 35-40% of the original ambient brightness. That is, regarding the ambient light, the light transmission rate of the shutter lenses operated under the open state is about 35-40%.
In the video output apparatus (e.g. a linear polarization or circular polarization display device), the image light output of the 3D image has a certain polarization direction, and the shutter lens structure of the shutter glasses which is used to collaborate with the video output apparatus has the same polarization direction. The polarizer in the shutter lens structure of the shutter glasses will therefore not cause the brightness of the original image light output to have a significant decrease. When the liquid crystal layer in the shutter lens structure of the shutter glasses is in an open state, only 10-20% of the brightness of the display area is filtered out by the polarizer, so about 65-70% of the original brightness of the display area finally reaches a user's eyes. That is, regarding the image light output of the display area, the light transmission rate of the shutter lens operated under the open state is about 65-70%. Since the shutter lens alternatively switches between the open state and closed state rather than constantly being in the open state the actual shutter-open period of the shutter glasses has an impact on the brightness of the ambient environment beyond the display area perceived by the user via the shutter glasses. Thus, the final brightness perceived by the user (i.e. the light transmission rate of the shutter lens) is substantially equal to the light transmission rate of the shutter lens operated under the open state multiplied by a ratio of the shutter-open period of the shutter lens to the whole glasses period (assuming that the liquid crystal layer can filter out any incoming light beams when in the closed state). The shutter lens operated under the open state has a light transmission rate of 35% for ambient light and has a light transmission rate of 70% for the image light output of the display area. When the ratio of the shutter-open period of the shutter lens to the whole glasses period is 16%, the final brightness of the display area the user feels is 11.2% (70%×16%). The final ambient brightness perceived by the user, however, is only 5.6% (35%×16%), which is lower than an acceptable level.
The shutter lens control mechanism employed by the conventional shutter glasses only takes 3D image viewing into consideration, and does not consider the ambient brightness perceived by the user. In other words, there is no function implemented for adjusting the ambient brightness perceived by the user. When the user perceives insufficient ambient brightness, they may fail to recognize objects (e.g. a keyboard or a remote control) beyond the display area of the video display apparatus.